Unlock Mii character for the Sonic Simulator

Unlock Super Sonic

To unlock Super Sonic, you must do two things..
First you must collect all 180 Red Rings from each of the 36 main acts, this will unlock all of the 2nd and 3rd Sonic Simulator acts.
Then you must clear all 21 of these Sonic Simulator stages at least once, you may do this as a single player.
Once you've done that, the options satellite on the main screen will glow, and give the option to use Super Sonic.
In Super Sonic mode, you collect 50 gold rings and activate the ability like wisp abilities.
Special wisp abilities will be disabled, and the stage design will change depending on this.
Super Sonic cannot be used in challenge mode.

Secrets

Extra Lives on results screen

After a level on the results screen you'll see the rank and the score you achieved.
Repeatedly jumping into, and dashing through the numbers will eventually break them, making them drop gold rings and at least 1 extra life.